1. Field of the Invention
The present invention relates to a voice coil type lens drive assembly for adjusting the focus of a lens by utilizing a repulsive magnetic force which a magnetic field created upon energization of a coil induces between the coil and a fixed magnet opposed to the coil.
2. Description of the Related Art
Heretofore, in connection with a voice coil type lens drive assembly for adjusting the focus of a lens by utilizing a repulsive magnetic force which a magnetic field created upon energization of a coil induces between the coil and a fixed magnet opposed to the coil, it is a usually way of doing that the lens is kept standstill at an initial position thereof with a spring having weak force when the coil is not energized.
For example, in Patent Literature 1 (Japanese Patent Laid-Open Publication No. 2005-128405, see FIG. 2 and paragraphs 0025, 0029) there is disclosed a construction to prevent deviation and movement in a rotational direction of a lens support in a completed state of assembly.
According to this conventional construction, as shown partially in FIG. 15 and as described concretely in paragraph 0025 of Patent Literature 1, an engaging projection 133 formed on an inner periphery surface of a frame 123 comes into engagement with an engaging recess 135 formed in an outer periphery surface of a cap 124 to inhibit the rotation of a lens support 107 in the circumferential direction. Consequently, deviation and movement in a rotational direction of the lens support 107 are prevented.
In an assembling operation, as is described in paragraph 0029, an inner periphery surface 11a of a rear spring 111 is attached to the lens support 107, then a magnet 113 and a coil 115 fixed to the lens support 107 are disposed in the interior of a yoke 103, and mounted to a base portion 105b of a base 105 via a rear spacer 117. Thereafter, an inner periphery-side end portion 109a of a front spring 109 is placed between a front spacer 121 and the yoke 103 and is fixed with the cap 124. Further, the frame 123 is mounted to the base 105 and an outer periphery-side end portion 109b is fixed with the frame 123.
As is seen from the above description, deviation and movement in the rotational direction of the lens support 107 are prevented in only a state substantially close to a completely assembled state wherein the frame 123 and the cap 124 are coupled together.
However, in the construction disclosed in Patent Literature 1, it is desired to remedy the following inconvenience although there is no special defect in function.
Since deviation and movement in the rotational direction of the lens support 107 are prevented in only a state substantially close to a completely assembled state, such deviation and movement cannot be prevented during assembly or during disassembly for repair.
Therefore, in the event an external force should act on the lens support 107 in such a process, the front spring 109 or the rear spring 11, as a spring having weak force acting when the coil is not energized, will be damaged, which is not desirable. Moreover, in the case where a projection is formed in the outer periphery direction of the lens support 107, it ends up with an increase in size of the outline of the lens drive assembly.